Quantification and Restoration of the Pre‐Drift Extension Across the NE Atlantic Conjugate Margins During the Mid‐Permian‐Early Cenozoic Multi‐Rifting Phases

Abstract

Continental rifting is associated with successive extensional phases, often leading to final continental breakup and initiation of oceanic spreading. Within the context of global plate tectonics, rifting is a fundamental process starting continent dispersal (Wilson, 1966), but instead paleogeographic models or plate reconstructions generally focus on post-breakup times. The main reason is that ocean spreading typically renders well constrained key

Structural analysis and measured extension in fault complexes along the Lofoten‐Vesterålen margin, offshore Norway, in the context of crustal‐scale rifting towards breakup in NE Atlantic

“…Paired conjugate crustal transects across the Lofoten‐Vesterålen and NE Greenland conjugate margins illustrating the post‐breakup crustal architecture and the extent of regional extensional phases (modified from Abdelmalak et al, 2022). Modelled underplating/magmatic addition (0% and 100% LCB scenarios) is illustrated only for the southern (a,b) and central (c,d) crustal transects, whereas no magma addition is modelled for the northern (e,f) crustal transects.…”

“…The paired conjugate profiles are described as the “southern transect” in the vicinity of the Bivrost Lineament and its conjugate counterpart, the “central transect” across the northern Lofoten segment/Vesterålen‐central Danmarkshavn Ridge, and the “northern transect” across the northern Andøya segment‐northern Danmarkshavn Ridge (Figure 6). The compiled crustal transects have been revised from Abdelmalak et al (2022), depict an updated representation of the entire crustal architecture, and are used for measuring total extension across the conjugate margins (see Supporting Information). The calculations derive through stretching and thinning factor measurements based on the thickness of the crystalline crust along each transect current (final stretched) length set from the continent‐ocean boundary (COB) position and compared to an initial reference crust thickness of 35 km of assumed unstretched continental crust (UCC) (Abdelmalak et al, 2022).…”

“…The compiled crustal transects have been revised from Abdelmalak et al (2022), depict an updated representation of the entire crustal architecture, and are used for measuring total extension across the conjugate margins (see Supporting Information). The calculations derive through stretching and thinning factor measurements based on the thickness of the crystalline crust along each transect current (final stretched) length set from the continent‐ocean boundary (COB) position and compared to an initial reference crust thickness of 35 km of assumed unstretched continental crust (UCC) (Abdelmalak et al, 2022). The COB was defined as the oceanward limit of the stretched continental crust based on the location of seafloor spreading magnetic anomalies in the oceanic crust and the landward limit of undisputed oceanic crust on seismic refraction profiles (Abdelmalak et al, 2022).…”

“…The central conjugate transect in the NE Greenland side (Danmarkshavn Ridge-central Tethys Basin transect) exhibits a current (final stretched) length of ca. 350 km, and includes a COB location that is defined at F I G U R E 6 Paired conjugate crustal transects across the Lofoten-Vesterålen and NE Greenland conjugate margins illustrating the postbreakup crustal architecture and the extent of regional extensional phases (modified from Abdelmalak et al, 2022). Modelled underplating/ magmatic addition (0% and 100% LCB scenarios) is illustrated only for the southern (a,b) and central (c,d) crustal transects, whereas no magma addition is modelled for the northern (e,f) crustal transects.…”

Tracing the Iceland plume and North East Atlantic breakup in the lithosphere

“…Accordingly, the domains composing the present-day passive continental margins of the NEA host up to 12 km thick Cretaceous to Paleocene sedimentary units and additional several km of pre-Cretaceous deposits [5][6][7] . However, the orientation of the breakup axis is oblique to the pre-existing Paleozoic/Mesozoic rift structures of the NEA and resulted in voluminous extrusive and intrusive igneous activities 8 .…”